1. Field of the Invention
The present invention generally relates to a data (content) search, and more particularly to a search memory, a memory search controller, and a memory search method for searching a large amount of data at a high speed.
2. Background of the Invention
Conventionally, a common content search is performed by, for example, the following steps. A database is sorted in ascending or descending order to create a table, and data is retrieved (i.e. referred to as “entry data”) at the center of the table. Given data (i.e. “search data”) is compared to the entry data. If the search data is after the entry data, subsequent entry data is selected and retrieved at the center of the latter half of the database. On the contrary, if the search data is prior to the entry data, subsequent entry data is selected and retrieved at the center of the former half of the database. The selected entry data from the latter or former half of the database is compared to the search data. The steps of comparison of the search data and the entry data, and the entry data selection are repeated to until the entry data matches the search data. This conventional method is called quick sort (quick search).
In this conventional search, it is required to read the entry data from memory that stores the database for each time the data is to be retrieved from the database (table), and to repeat reading and comparison of the data. This takes a long time for a search of massive entry data like a database. To shorten the search time, the repetitions of reading and comparison have to be done quickly. These repetitions may be made faster by executing multiple searches simultaneously (i.e. in parallel). However, since a Central Processing Unit (CPU) performs the comparison in conventional techniques, simultaneous execution of multiple searches will require combinations of multiple CPUs and memory units.
Thus, searching a large amount of data at a high speed without requiring combinations of multiple CPUs and memory units is desired.